中文摘要：

本文通过围隔试验研究了淡水腹足纲动物铜锈环棱螺（Bellamya aeruginosa）对藻华水体中浮游动物群落的影响。实验根据铜锈环棱螺生物量设置了高、中和低3个密度组和一个不投放螺的对照组。分别于试验开始后0、3、7、11、15、23、31、46和61 d采集样品并计数浮游动物的种类和数量。结果表明：试验期间共鉴定出浮游动物33属52种,其中原生动物15种、轮虫28种、枝角类6种、桡足类3种;桡足类无节幼体、晶囊轮虫（Asplanchra）、多肢轮虫（Polyarthra）和臂尾轮虫（Brachionus）为浮游动物优势类群;主响应曲线分析显示,所有处理组中的浮游动物群落均与对照组存在显著差异;铜锈环棱螺的存在显著减少了有壳肉足虫、砂壳纤毛虫和轮虫种群数量,其中丰度降低最多的为螺形龟甲轮虫（Keratella cochlearis）、曲腿龟甲轮虫（Keratella valga）和砂壳虫（Difflugia sp.）,在高密度组中的数量分别由试验开始时的481、545.3和359.7 ind·L^-1下降至试验结束时的0.1、0.1和9.2 ind·L^-1;铜锈环棱螺的存在还导致高密度组中剑水蚤（Cyclops sp.）的数量由试验开始时的46.4 ind·L^-1增加至试验结束时的420.1 ind·L^-1。这些结果说明,铜锈环棱螺的存在显著影响了藻华水体中浮游动物的群落动态,而这些影响更多的是来自于铜锈环棱螺的间接影响而不是直接滤食。

英文摘要：

The purpose of this microcosm experiment was to determine whether the freshwater gastropod Bellamya aeruginosa affected zooplankton community in the water body experiencing a cyanobacterial bloom. Three treatments of different snail densities （low, medium, and high） and a control （no snails） were set up. The abundance of zooplankton was determined on days 0, 3, 7, 11, 15, 23, 31, 46, and 61. A total of 52 species from 33 genera were identified, which consisted of 15 species of Protozoa, 28 species of Rotifera, 6 species of Cladoera and 3 species of Copepoda. According to the abundance and occurrence, nauplius, Asplanchra, Polyarthra, and Brachionus were considered as the dominant taxa. Principal response curves showed that zooplankton community in all treatments was consistently different from that in the control. The highest decrease in abundance was found for Keratella cochlearis, K. valga and Difflugia sp. The abundances of these species decreased from 481, 545.3 and 359.7 ind·L^-1 to 0.1, 0.1 and 9.2 ind·L^-1 in the high density treatment, respectively. The populations of testate amoebae, tintinnid ciliate and rotifer were significantly negatively affected by the snails. Additionally, the presence of snails also caused the increase in the biomass of Cyclops sp. The abundance of Cyclops sp. increased from 46.4 ind·L^-1 to 420.1 ind·L^-1 in the high density treatment. These results indicate that the presence of snails resulted in a significant change of zooplankton community in cyanobacterial bloom. The dynamic of zooplankton community was more subject to the indirect impact than direct filterfeeding of snails.